Transmission device

ABSTRACT

A method in a communication system, where a systematic code obtained by systematic encoding of information bits having dummy bits inserted and by deletion of the dummy bits from results of the systematic encoding is transmitted. On a receiving side, the deleted dummy bits are inserted into the received systematic code and then decoded. The method includes: deciding a size of dummy bits for insertion into information bits; segmenting the information bits into a number of code blocks when a bit size of the information bits is greater than a stipulated size; inserting dummy bits into each block of the segmented information bits in conformity with a dummy bit insertion pattern; performing systematic encoding of each block of the information bits into which the dummy bits are inserted, and deleting the dummy bits from the results of the systematic encoding to generate a systematic code.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.12/068,717, filed Feb. 11, 2008, now pending, which is a continuation ofInternational Application No. PCT/JP2005/014823, filed Aug. 12, 2005,the contents of each are herein wholly incorporated by reference. Thispresent application also relates to U.S. Ser. No. 13/345,969, filed Jan.9, 2012.

This invention relates to a transmission device, and in particularrelates to a transmission device in a system in which dummy bits areinserted into information bits and encoding is performed to generate asystematic code, then dummy bits are deleted from the systematic codeand the result is transmitted, and, on the receiving side,maximum-likelihood dummy bits are inserted and decoding is performed.

As shown in FIG. 35, a code is called a systematic code when, uponcreating an N-bit code I₂ by encoding information bits I₁ comprising Kbits, K bits among the code comprise the original information; theremaining M (=N−K) bits are called parity bits. Turbocodes are oneexample of systematic codes.

As the general format of bits, an information alphabet is considered.One alphabet takes as values q types of symbols {a₀, a₁, a₂, . . . ,a_(q-1)}; bit is a special case of alphabet in which q=2 and a₀=0, a₁=1.

On the transmitting side, if a K×N generator matrix,

G=(gij); i=0, . . . ,K−1; j=0, . . . ,N−1

is used with K information alphabet elements u=(u₀, u₁, . . . , u_(K-1))in the following equation,

x=uG

to generate a code alphabet x consisted of N code alphabet elements x₀,x₁, . . . , x_(N-1) (x=(x₀, x₁, . . . , x_(N-1))), then this codealphabet x is a block code, and the information alphabet elements u areblock-encoded.

On the receiving side, the information alphabet elements u are estimatedfrom the data received for the block code (code vector)x. To this end,the following parity check equation for x is used:

xH ^(T)=0

Here, H=(hij); i=0, . . . , M−1; j=0, . . . , N−1, is a parity checkmatrix, and H^(T) is the transpose of H (with the rows and columnsinterchanged). From the above two equations, H and G satisfy thefollowing relation.

GH ^(T)=0

From this, if either H or G is given, then the encoding rules areuniquely determined.

FIG. 36 shows the configuration of a communication system in which blockencoding is performed in the transmitter and decoding is performed inthe receiver; the transmitter 1 comprises an encoding portion 1 a, whichencodes information u of K bits to generate an N-bit block code x, and amodulation portion 1 b which modulates and transmits the block code. Thereceiver 2 comprises a demodulation portion 2 a, which demodulates thesignal received via a transmission path 3, and a decoding portion 2 b,which decodes the N bits of received information to obtain the originalK bits of transmitted information.

The encoding portion 1 a comprises a parity generator 1 c, whichgenerates M (=N−K) parity bits p, and a P/S conversion portion 1 d,which combines the K bits of information u and M parity bits p andoutputs N (=K+M) block code elements x. As the code of the encodingportion 1 a, for example, a turbocode can be adopted. The decodingportion 2 b comprises a decoder 2 c, which performs error detection andcorrection processing of the received likelihood data y and performsdecoding to restore the original transmitted K bits of information andoutputs estimation information. The block code x transmitted from thetransmitter 1 is affected by the transmission path 3, and so is notinput to the decoder 2 c in the form transmitted, but is input to thedecoder 2 c as likelihood data. The likelihood data comprisesreliabilities as to whether a code bit is 0 or 1, and signs (indicating“0” if +1 and “1” if −1). The decoder 2 c performs stipulated decodingprocessing based on the likelihood data for each signed bit, to estimatethe information bits u. In the case of a turbocode, the decoder 2 cperforms maximum a posteriori probability (MAP) decoding.

FIG. 37 shows the configuration of a turbo encoding portion 1 a; FIG. 38shows the configuration of a turbo decoding portion 2 b. A turboencoding portion is a systematic encoder comprising a number of elementencoders and an interleaver; by adopting MAP decoding, decoding resulterrors can be reduced by increasing the number of decoding repetitions.

FIG. 37 is one such example; in this encoder, two element encoders arearranged in parallel with one interleaver therebetween. Here u=[u0, u1,u2, u3, . . . , u_(K-1)] is the information data for transmission, oflength K; xa, xb, xc are encoded data resulting from encoding of theinformation data u by the turbo encoder 1 a; ya, yb, yc are receivedsignals, resulting from propagation of the encoded data xa, xb, xc overthe communication path 3, and are affected by noise and fading; and u′is the result of decoding of the received data ya, yb, yc by the turbodecoder 2 b. In the turbo encoder 1 a, the encoded data xa is theinformation data u itself; the encoded data xb is data resulting fromconvolution encoding of the information data u by a first elementencoder ENC1; and the encoded data xc is data resulting frominterleaving (π) of the information data u and convolution encoding by asecond element encoder ENC2. That is, the turbo encoder performssystematic encoding using two convolutions; xa is the information data,and xb and xc are parity data. The P/S conversion portion 1 d convertsthe encoded data xa, xb, xc into a series and outputs the result.

In the turbo decoder 2 b of FIG. 38, the first element decoder DEC1performs decoding using ya and yb among the received signals ya, yb, yc.The first element decoder DEC1 is a soft decision-output elementdecoder, which outputs likelihoods of decoding results. Next, the secondelement decoder DEC2 similarly performs decoding using yc and thelikelihoods output from the first element decoder DEC1. The secondelement decoder DEC2 is also a soft decision-output element decoder,which outputs likelihoods of decoding results. In this case, yc is thereceived signal corresponding to xc, which results from interleaving andencoding the original data u; hence likelihoods output from the firstelement decoder DEC1 are interleaved (π) before input to the secondelement decoder DEC2. Likelihoods output from the second element decoderDEC2 are deinterleaved (π⁻¹), and are then input to the first elementdecoder DEC1 as feedback. The “0” and “1” hard decision results of thedeinterleaving results of the second element decoder DEC2 are taken tobe the turbo decoding results (decoded data) u′. Thereafter, byrepeating the above decoding operation a prescribed number of times, theerror rate of the decoding result u′ can be reduced. MAP elementdecoders can be used as the first and second element decoders DEC1, DEC2in the turbo decoder.

A 3GPP W-CDMA mobile communication system may be considered as aconcrete form of the communication system of FIG. 36. FIG. 39 shows theconfiguration of a 3GPP W-CDMA mobile communication system; the wirelessbase stations are transmitters of FIG. 36, and the mobile station is areceiver. In FIG. 39, the mobile communication system comprises a corenetwork 11, wireless base station control devices (RNC, radio networkcontrollers) 12, 13, demultiplexing devices 14, 15, wireless basestations (Node B) 16 ₁ to 16 ₅, and a mobile station (UE, userequipment) 17.

The core network 11 is a network which performs routing within themobile communication system, and can for example be configured as an ATMswitching network, packet-switched network, router network, or similar.The core network 11 is also connected to other public networks (PSTN),and the mobile station 7 can also communicate with fixed telephone setsand similar.

The wireless base station control devices (RNCs) 12, 13 are positionedas higher-level devices relative to the wireless base stations 16 ₁ to16 ₅, and are provided with functions for controlling these wirelessbase stations 16 ₁ to 16 ₅ (ex. Function for managing wireless resourcesused, and similar). The demultiplexing devices 14, 15 are providedbetween the RNCs and the wireless base stations, and separate signalsaddressed to each of the wireless base stations received from the RNCs12, 13, for output to the respective wireless base stations, as well asexecuting control to multiplex signals from the wireless base stationsand pass the signals to the RNCs.

Wireless resources of the wireless base stations 16 ₁ to 16 ₃ aremanaged by the RNC 12, and wireless resources of the wireless basestations 16 ₄ and 16 ₅ are managed by the RNC 13, while the basestations perform wireless communication with the mobile station 17. Whenthe mobile station 17 exists within the wireless area of the wirelessbase stations 16 _(i), a wireless connection with the wireless basestations 16 _(i) is established, and communication with othercommunication devices is performed via the core network 11.

The above is an explanation of a general mobile communication system; inorder to enable high-speed downlink-direction data transmission (packettransmission), a HSDPA (High Speed Downlink Packet Access) method isadopted.

HSDPA employs an adaptive encoding modulation method, and ischaracterized by the fact that the number of bits in the transport blockTrBL, number of multiplex codes, and modulation method (QPSK modulation,16QAM modulation) are switched adaptively according to the wirelessenvironment between the wireless base station and the mobile station.

Further, HSDPA adopts an H-ARQ (Hybrid Automatic Repeat reQuest) method.In H-ARQ, when an error is detected by the mobile station in datareceived from a wireless base station, resending is requested (a NACKsignal is sent) to the wireless base station. Upon receiving this resendrequest, the wireless base station resends the data, and so the mobilestation uses both the data already received and the resent received datato perform error correction decoding. In this way, in H-ARQ previouslyreceived data is effectively utilized even when there are errors, sothat the gain of error-correction decoding is increased, andconsequently the number of resends can be kept small. When an ACK signalis received from a mobile station, there is no longer a need forresending since data transmission has been successful, and so the nextdata is transmitted.

The main wireless channels used in HSDPA are, as shown in FIG. 40, (1)HS-SCCH (High Speed-Shared Control Channel), (2) HS-PDSCH (HighSpeed-Physical Downlink Shared Channel), and (3) HS-DPCCH (HighSpeed-Dedicated Physical Control Channel).

HS-SCCH and HS-PDSCH are shared channels in the downlink direction, thatis, from wireless base stations to mobile stations; HS-PDSCH is a sharedchannel which transmits packets in the downlink direction, while HS-SCCHis a control channel which transmits various parameters relating to datatransmitted in HS-PDSCH. In other words, HS-SCCH is a channel used fornotification of the transmission of data via HS-PDSCH; the variousparameters are the destination mobile station information, transmissionbitrate information, modulation method information, number of spreadingcodes allocated (number of codes), rate matching patterns for thetransmission data, and other information.

HS-DPCCH is a dedicated control channel in the uplink direction, thatis, from mobile stations to wireless base stations, and is used whentransmitting, from mobile stations to wireless base stations, thereception results (ACK signals, NACK signals) for data received viaHS-PDSCH. HS-DPCCH is also used to transmit CQI (Channel QualityIndicator) values, based on the reception quality of signals receivedfrom wireless base stations, to wireless base stations. By receiving CQIvalues, the wireless base stations can judge the quality of downlinkwireless environments, and if an environment is satisfactory, can switchto a modulation method enabling faster data transmission, but if theenvironment is poor, can switch to a modulation method for slower datatransmission, and by this means can perform adaptive modulation. Inactuality, a base station has a CQI table which defines formats withdifferent transmission speeds according to CQI values of 1 to 30;parameters (transmission rate, modulation method, number of multiplexingcodes, and similar) are determined according to the CQI value by makinga reference to the CQI table, and are notified mobile stations byHS-SCCH, while in addition data is transmitted to mobile stations usingHS-PDSCH based on the parameters.

In the above-described 3GPP W-CDMA mobile communication system, thetransmitter 1 and the receiver 2 in FIG. 36 are a wireless base stationand a mobile station (mobile terminal) respectively.

FIG. 41 shows the data transmission processing block of a 3GPP W-CDMAwireless base station, and FIG. 42 shows the data format used inexplanation of transmission processing (see 3GPP, TS25.212v5.9.0). Anexample is shown for which the number of code blocks is 2, both 1stRM 25b and 2 nsRM 25 c in the physical layer H-ARQ function portion 25 arepuncturing, and the number of physical channel codes is 2.

(1) Information bits are passed from the upper layer to the wirelessbase station as a transport block (TB).

(2) The CRC addition portion 21 performs encoding for detection oferrors by CRC (Cyclic Redundancy Check) in transport block (TB) units.That is, based on a transport block TB, a specified number of CRC paritybits are generated, and these are added after the transport block TBitself. (data set D1)

(3) Then, the bit scrambling portion 22 performs bit scrambling of thedata set D1. In bit scrambling, bitwise addition of a pseudorandom bitpattern B=(b0, . . . , b(K−1)), generated by a stipulated generationmethod and of the same size K as the data set D1, and the data set D1 isperformed (hereafter, arithmetic operations on bits are always taken tomean mod 2 operations on {0,1}). (data set D2)

(4) The code block segmentation portion 23 performs code blocksegmentation of the data set D2. That is, if the size K of the data setD2 exceeds a stipulated size Z, the data set D2 is segmented to obtain aplurality of code blocks all of the same data size. If the data cannotbe divided evenly by the number of code blocks C, filler bits are addedto adjust the size. Filler bits are of value 0, and are added to thebeginning of the original data. In turbo encoding, 40≦K≦5114, so thatZ=5114. (data set D3)

(5) The channel coding portion (encoding portion) 24 performs encodingof each of the code blocks of the data set D3. Encoding uses a turbocodeat the stipulated code rate R=⅓. (data set D4)

(6) The physical layer HARQ function portion 25 performs H-ARQprocessing (H-ARQ functionality) for the data set D5. The bitsegmentation portion 25 a of the physical layer HARQ function portion 25divides each of the code blocks output from the encoding portion 24 intosystematic bits, parity bits 1, and parity bits 2, and seriallyconcatenates bits of the same type. (data set D5)

(7) The first rate matching portion 25 b of the physical HARQ functionportion 25 checks whether the total bit length of data set D5 is largerthan the stipulated buffer size NIR, and if larger, performs puncturingof the data set D5 such that the size becomes the NIR size, but ifsmaller than NIR, does nothing. Puncturing is performed for parity 1 andparity 2, but is not performed for systematic bits. (data set D61)

Next, the second rate matching portion 25 c of the physical layer HARQfunction portion 25 performs rate matching (repetition or puncturing) ofthe data set D61 according to specified H-ARQ transmission parameters.H-ARQ transmission parameters may include: modulation method (QPSK or16QAM), physical channel HS-PDSCH total bit size Ndata, H-ARQtransmission pattern RV and so on.

The total bit size Ndata is given by

Ndata=number of codes×physical channel size

and the physical channel size is 960 for QPSK and 1920 for 16QAM. Whenthe size of the data set D61 is smaller than Ndata, the second ratematching portion 25 c performs repetition such that the size of the dataset D61 is equal to Ndata; when larger than Ndata, puncturing isperformed. (data set D62)

In repetition, a specified number of bits are selected from among thecode bits, a copy is created and is added; on the receiving side,diversity combining of the same data bits is performed so as to improvethe SN. In puncturing, a specified number of bits are selected fromamong the code bits, and these bits are deleted; on the receiving side,fixed likelihood maximum values are added as data for the deleted bitpositions.

Of the above parameters, the receiver (terminal) is notified of themodulation method, number of codes, RV and similar via the separateshared channel HS-SCCH.

(8) The bit collection portion 25 d of the physical layer HARQ functionportion 25 performs bit collection of the data set D62, and outputscollection results. Then, the bit collection portion 25 d performssubstitution of the data order so as to map systematic bits and paritybits to one modulation signal symbol.

This substitution processing is one type of interleaving. That is, withthe number of bits mapped to one modulation signal symbol as the numberof columns Ncol, and the number of rows Nrow=Ndata/Ncol, the Ndata databits are arranged in a matrix. In the case of QPSK, Ncol=2; for 16QAM,Ncol=4. In the above substitution processing, the systematic bitplacement area and parity bit placement area are divided such thatsystematic bits are in the upper rows. For example, in the case of16QAM, in this substitution processing systematic bits arepreferentially mapped to the first two bits of the four bits. This isbecause 16QAM mapping stipulates that reliability of the likelihood forthe leading two bits be high. The bits in each column of the matrix formone modulation signal symbol. (data set D7)

(9) The physical channel segmentation portion 26 performs physicalchannel segmentation of the data set D7. The number of divisions is theabove number of codes. The data set D7 is serially segmented from theleading bit into this number of divisions. (data set D8)

(10) The HS-PDSCH interleaving portion 27 performs H-ARQ interleaving ofthe data set D8. That is, the interleaving portion 27 performsinterleaving of the physical channels using a stipulated interleavepattern. (data set D9)

(11) The constellation rearrangement portion 28 performs constellationrearrangement of the data set D9 when the modulation method is 16QAM.However, when the modulation method is QPSK, no action is taken. Insymbol rearrangement, bit substitution and inversion are performed foreach symbol in four-bit units according to the specified parameters.(data set D10)

(12) The physical channel mapping portion 29 performs physical channelmapping of the data set D10, and passes the physical channel data ofdata set D10, unmodified, to the modulation portion.

As the encoding/decoding method for the systematic code, in order toimprove the error rate characteristic of the decoded results, technologyhas been proposed in which, on the transmitting side, dummy bits areinserted into information bits and encoding is performed, then the dummybits are deleted from the code thus obtained to generate a systematiccode, and the systematic code is transmitted (see PCT/JP 2005/367 andTokuhyo No. 2004-531972 (JP2004-531972), paragraph 0104). FIG. 43explains the encoding/decoding method proposed in PCT/JP 2005/367.

Into the K information bits 100 are inserted K0 dummy bits 200 in aprescribed pattern, to obtain K1 (=K+K0) bits of first information. Thedummy bits are not limited to an all-“1”s pattern or to a repeatedalternation of “1”s and “0”s, as in “1010 . . . 10”, and any prescribedpattern can be used. The dummy bits 200 can be added before or behindthe information bits 100, or can be inserted uniformly among theinformation bits. In the figure, the dummy bits 200 are inserted afterthe information bits 100.

Then, the information bits of the K1 bits are used to create M paritybits 300, which are added to the K1 bits to generate N1 (=K1+M) bits ofinformation 400 (systematic encoding such as turbo encoding).Thereafter, the K0 dummy bits 200 are deleted from this information togenerate N (=K+M) bits of a systematic code 500; this systematic code500 is transmitted from the transmitter to the receiver, and decoding isperformed at the receiver. The code rate is R=K/(K+M).

The decoding portion of the receiver inserts the dummy bits 200 deletedon the transmitting side into the demodulated systematic code 500 asmaximum probabilities (reliability ∞), and then performs turbo decodingand outputs information bits 100.

FIG. 44 shows the configuration of a communication system which realizesthe encoding/decoding method of FIG. 43; portions which are the same asin FIG. 36 are assigned the same symbols. The encoding portion 1 a ofthe transmitter 1 applies forward error correction (FEC) to theinformation bits u, in order to perform transmission with highreliability, the modulation portion 1 b modulates the resulting codebits x, and the modulated signals are transmitted to the receiver 2 viathe wireless propagation path 3. The demodulation portion 2 a of thereceiver demodulates the received data, and inputs to the decodingportion 2 b likelihood data y comprising reliabilities as to whethercode bits are “0” or “1” and symbols (+1→0, −1→1). The decoding portion2 b performs stipulated decoding processing based on the likelihood datafor each code bit, and estimates the information bits u.

In the encoding portion 1 a of the transmitter 1, the dummy bitinsertion portion 1 e inserts K0 randomly selected bits 0, 1 as dummybits at randomly selected positions in the K information bits u, andoutputs K1=K+K0 information bits

(u,a)=(u ₀ , . . . ,u _(K-1) , a ₀ , . . . ,a _(K0-1))

The encoder 1 f performs turbo encoding using the K1 information bitswith the dummy bits inserted, and outputs N1 (=K+K0+M) information bitsx₁(u,a,p). Here p are M parity bits,

p=(p ₀ , . . . ,p _(M-1))

The dummy bit deletion portion 1 g deletes the K0 dummy bits a from theN1 information bits x₁(u,a,p) output from the encoder 1 f, to generatethe N information bits

x=(u,p)=(x ₀ ,x ₁ , . . . ,x _(N-1))

The modulation portion 1 b modulates the information bits x andtransmits the result.

The demodulation portion 2 a of the receiver 20 receives the data, whichhas passed through the propagation path 3 and had noise added, performsdemodulation, and inputs to the decoding portion 2 b the likelihood datafor each code bit

y=(y ₀ ,y ₁ , . . . ,y _(N-1))

The dummy bit likelihood insertion portion 2 d of the decoding portion 2b inserts likelihood data a with maximum likelihood (reliability ∞) atthe positions at which dummy bits were inserted at the transmitter, andinputs the result, as N1 (=N+K0) likelihood data items, to the decoder 2e. The decoder 2 e performs turbo decoding of the N1 likelihood dataitems (y, a), and outputs information bit estimation results.

In this way, by appropriately inserting and deleting dummy bits on thetransmitting and on the receiving sides, decoding errors can bedecreased.

When the above method is applied to a wireless base station comprisingthe transmission processing portion shown in FIG. 41, exactly how dummybits are inserted and deleted poses a problem.

In particular, the encoding device must be configured taking intoconsideration the dummy bit insertion/deletion positions, whether tomake the code rate fixed or variable, whether to segment code blocks,the size after dummy bit insertion, and other matters.

Further, dummy bits must be inserted into information bits so as toeffectively reduce decoding errors.

Further, upon encoding, when for example a turbocode is used forencoding with interleaving and deinterleaving, dummy bits must beinserted into information bits such that decoding errors are effectivelyreduced with interleaving and deinterleaving taken into account.

SUMMARY OF THE INVENTION

Hence an object of this invention is to provide various transmissiondevices which take into account dummy bit insertion/deletion positions,whether to make the code rate fixed or variable, whether to segment codeblocks, the size after dummy bit insertion, and other matters.

A further object of the invention is to insert dummy bits intoinformation bits so as to enable effective reduction of decoding errors.

A further object of the invention, in the case of a code in whichinterleaving and deinterleaving is performed upon encoding, such as inthe case of a turbocode, is to insert dummy bits at information bitpositions such that decoding errors can be effectively reduced withinterleaving and deinterleaving taken into account.

A further object of the invention is to insert dummy bits intoinformation bits such that decoding errors can be reduced, and moreoverthe code rate is the required value.

By means of this invention, the above objects are attained by atransmission device, in a communication system in which a systematiccode, resulting from systematic encoding of information bits into whichdummy bits are inserted and the dummy bits then deleted, is transmitted,and on the receiving side the dummy bits deleted on the transmittingside are inserted into the received systematic code and then decoding isperformed.

A first transmission device of the invention comprises a segmentationportion, which, based on a specified code rate, or based on the physicalchannel transmission rate, decides the size of dummy bits for insertioninto information bits, and when the total size of the information bitsand the dummy bits is greater than a stipulated size, performssegmentation of the information bits; a dummy bit insertion portion,which inserts dummy bits into each block of the segmented informationbits; a systematic code generation portion, which performs systematicencoding of each block if the segmented information bits into which thedummy bits are inserted, and also deletes the dummy bits from theresults of the systematic encoding to generate a systematic code; and, atransmission portion, which transmits the systematic code.

A second transmission device of the invention comprises a dummy bitinsertion portion, which, based on a specified code rate, or based onthe physical channel transmission rate, decides the size of dummy bits,and inserts the dummy bits into the information bits; a segmentationportion, which, when the total size of the information bits and dummybits is greater than a stipulated size, performs segmentation of theinformation bits into which the dummy bits are inserted to pluralblocks; a systematic code generation portion, which performs systematicencoding of each block and deletes the dummy bits from the results ofthe systematic encoding to generate a systematic code; and, atransmission portion, which transmits the systematic code.

By means of the first and second transmission devices, by inserting thedummy bits the code characteristics can be improved, and moreover thedummy bits can be inserted such that the code rate is the required coderate, or such that the code length is made to correspond to the physicalchannel transmission rate.

In the first transmission device, the dummy bit insertion portioninserts the same number of dummy bits in the same positions in eachblock of the segmented information bits. By this means, the codecharacteristics can be improved.

In the second transmission device, the dummy bit insertion portionuniformly inserts the dummy bits into each of the segmented informationbits, and inserts the same number of dummy bits in the same positions ineach block of the segmented information bits. By this means, the codecharacteristics can be improved.

A third transmission device of the invention comprises a dummy bitinsertion portion, which inserts dummy bits into information bits; anencoding portion, which uses the information bits into which the dummybits are inserted to generate parity bits, adds the parity bits to theinformation bits to generate a systematic code and outputs thesystematic code; a puncturing portion, which, when the code length isgreater than a stipulated size, performs puncturing of the parity bits;a dummy bit deletion portion, which in parallel with the puncturingdeletes the dummy bits inserted into the information bits of thesystematic code; and, a transmission portion, which transmits thesystematic code with the dummy bits deleted.

By means of the third transmission device, because the information bits(referred to as systematic bits) are already separated, the dummy bitscan easily be deleted from the systematic bits. Further, becauseprocessing to delete the dummy bits from the systematic bits can beperformed simultaneously with puncturing of the parity bits of thesystematic code, the dummy bit deletion does not affect the overalltransmission processing time.

A fourth transmission device of the invention comprises a dummy bitinsertion portion, which inserts dummy bits into information bits; anencoding portion, which uses the information bits into which the dummybits are inserted to generate parity bits, and moreover deletes thedummy bits inserted into the information bits, adds the parity bits tothe information bits from which the dummy bits are deleted to generate asystematic code, and outputs the systematic code; and, a transmissionportion, which transmits the systematic code from which the dummy bitsare deleted. When dummy bits are deleted within the encoding portion inthis way, because the information bits (referred to as systematic bits)are already separated, the dummy bits can easily be deleted from thesystematic bits.

A fifth transmission device of the invention comprises a dummy bit sizedecision portion, which calculates the size of dummy bits based on aspecified code rate, and when the total size of the information bits andthe dummy bits is greater than a stipulated size, reduces the size ofthe calculated dummy bits by the difference between the total size andthe stipulated size; a dummy bit insertion portion, which inserts thedecided number of dummy bits into the information bits; a systematiccode generation portion, which performs systematic encoding of theinformation bits into which the dummy bits are inserted, and thendeletes the dummy bits from the results of the systematic encoding togenerate a systematic code; and, a transmission portion, which transmitsthe systematic code.

By means of the fifth transmission device, the dummy bits can beinserted, and in addition, when a code block is segmented, the maximumnumber of dummy bits can be inserted.

A sixth transmission device of the invention comprises a scramblingportion, which performs scrambling processing of information bits towhich error correction codes have been added; a dummy bit insertionportion, which inserts dummy bits into information bits either beforethe scrambling processing, or after the scrambling processing; asystematic code generation portion, which performs systematic encodingof the information bits into which the dummy bits are inserted, anddeletes the dummy bits from the results of the systematic encoding togenerate a systematic code; and, a transmission portion, which transmitsthe systematic code. By means of the sixth transmission device, dummybits can be inserted either before bit scrambling, or after bitscrambling.

A seventh transmission device of the invention comprises a dummy bitinsertion portion, which inserts dummy bits into information bits; asystematic code generation portion, which performs systematic encodingof information bits into which the dummy bits are inserted, and thendeletes the dummy bits from the results of the systematic encoding togenerate a systematic code; and, a transmission portion, which transmitsthe systematic code; the dummy bit insertion portion performs uniforminsertion of the dummy bits into the information bits such that thecontinuous length of the dummy bits is equal to or less than a presetlength. By performing insertion of the dummy bits into the informationbits such that the continuous length of dummy bits is equal to or lessthan a preset length, decoding characteristics can be improved.

Because the decoding characteristics are satisfactory within the rangesof a stipulated number of bits from the beginning and from the end ofthe information bits, the dummy bit insertion portion of the seventhtransmission device executes control such that dummy bits are notinserted in this range. By this means, decoding characteristics can beimproved.

By considering the internal interleave pattern of a turbocode, originalbit positions which, after interleaving, exists within the ranges of astipulated number of bits from the data beginning and end, aredetermined in advance, and the dummy bit insertion portion executescontrol such that the dummy bits are not inserted in these original bitpositions. By this means, decoding characteristics can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the configuration of the transmission processing portion ofthe wireless base station of a first embodiment;

FIG. 2 explains dummy bit insertion processing in the first embodiment;

FIG. 3 explains dummy bit deletion processing in the first embodiment;

FIG. 4 shows the configuration of the code block segmentation portion inthe first embodiment;

FIG. 5 shows the configuration of the turbo encoding portion;

FIG. 6 explains dummy bit insertion processing in the wireless basestation of a second embodiment;

FIG. 7 is a block diagram of principal portions of the secondembodiment;

FIG. 8 shows the flow of dummy bit insertion processing in the secondembodiment;

FIG. 9 explains the method of dummy bit insertion after codesegmentation in the second embodiment;

FIG. 10 shows the flow of dummy bit insertion processing in the secondembodiment;

FIG. 11 explains the insertion method of inserting dummy bits beforecode segmentation;

FIG. 12 explains the dummy bit insertion processing of a thirdembodiment;

FIG. 13 shows the flow of dummy bit insertion processing in the thirdembodiment;

FIG. 14 explains the dummy bit insertion processing of a fourthembodiment;

FIG. 15 shows the flow of dummy bit insertion processing in the fourthembodiment;

FIG. 16 explains the dummy bit insertion processing of a fifthembodiment;

FIG. 17 shows the flow of dummy bit insertion processing in the fifthembodiment;

FIG. 18 explains the dummy bit insertion processing of a sixthembodiment;

FIG. 19 is a block diagram of principal portions of the transmissionprocessing portion in the sixth embodiment;

FIG. 20 shows the flow of dummy bit insertion processing in the sixthembodiment;

FIG. 21 explains dummy bit insertion in a seventh embodiment;

FIG. 22 is a block diagram of principal portions of the transmissionprocessing portion in the seventh embodiment;

FIG. 23 shows the flow of dummy bit insertion processing in the seventhembodiment;

FIG. 24 is an example of a random pattern of dummy bit values in theseventh embodiment;

FIG. 25 is an example of a dummy bit insertion pattern in an eighthembodiment;

FIG. 26 explains dummy bit insertion positions;

FIG. 27 explains dummy bit insertion positions taking interleaving intoconsideration;

FIG. 28 shows Eb/N0 characteristics (decoding characteristics) requiredfor different code rates;

FIG. 29 shows the configuration of the transmission processing portionin the wireless base station of a ninth embodiment;

FIG. 30 explains the dummy bit insertion position pattern in a tenthembodiment;

FIG. 31 shows the flow of dummy bit position modification in the tenthembodiment;

FIG. 32 explains dummy bit position modification in the tenthembodiment;

FIG. 33 shows the configuration of the turbo encoder of an eleventhembodiment;

FIG. 34 shows the configuration of the turbo decoding portion of theeleventh embodiment;

FIG. 35 explains systematic codes;

FIG. 36 shows the configuration of a communication system of the priorart, in which block encoding is performed in the transmitter anddecoding is performed in the receiver;

FIG. 37 shows the configuration of a turbo encoder portion;

FIG. 38 shows the configuration of a turbo decoder portion;

FIG. 39 shows the configuration of a 3GPP W-CDMA mobile communicationsystem;

FIG. 40 explains shared channels in HSDPA;

FIG. 41 is a block diagram of the transmission processing portion in a3GPP W-CDMA wireless base station;

FIG. 42 is a data format used to explain transmission processing;

FIG. 43 explains an encoding/decoding method using dummy bits; and,

FIG. 44 shows the configuration of a communication system which realizesthe encoding/decoding method of FIG. 43.

DESCRIPTION OF THE PREFERRED EMBODIMENTS (A) First Embodiment

FIG. 1 shows the configuration of the transmission processing portion 30of the wireless base station of a first embodiment; portions which arethe same as in the transmission processing portion of the prior artshown in FIG. 41 are assigned the same symbols. The transmissionprocessing portion 30 transmits information such as packets to a mobilestation by means of the HSDPA shared channel HS-PDSCH.

The transmission processing portion 30 comprises a CRC addition portion21; bit scrambling portion 22; code block segmentation portion 23; dummybit insertion portion 31; channel coding portion (encoding portion) 24;physical layer HARQ function portion 25; physical channel segmentationportion 26; HS-PDSCH interleaving portion 27; constellationrearrangement portion 28; physical channel mapping portion 29; andtransmission portion 32 which transmits information. The dummy bitinsertion portion 31 is provided between the code block segmentationportion 23 and the encoding portion 24, and inserts dummy bits intoinformation bits.

The physical layer HARQ function portion 25 comprises a bit segmentationportion 25 a, first rate matching portion 25 b, second rate matchingportion 25 c, and bit collection portion 25 d. The first rate matchingportion 25 b comprises, in addition to rate matching portions 25 b-1, 25b-2 for parity 1 and 2, a dummy bit deletion portion 25 b-3, whichdeletes dummy bits from the systematic bits; similarly to the prior art,the second rate matching portion 25 c comprises rate matching processingportions 25 c-1, 25 c-2 for parity 1 and 2, and a systematic bit ratematching processing portion 25 c-3.

The dummy bit deletion portion 25 b-3 deletes dummy bits which have beeninserted into systematic bits by the dummy bit insertion portion 31. Inthe prior art, the first rate matching portion 25 b passes systematicbits without performing any processing; but in the first embodiment,dummy bit deletion processing is performed by the dummy bit deletionportion 25 b-3 simultaneously with puncturing of parity bits 1, 2 by therate matching processing portions 25 b-1 and 25 b-2.

FIG. 2 explains dummy bit insertion processing, and FIG. 3 explainsdummy bit deletion processing. The code block segmentation portion 23performs code block segmentation of the data set D2 resulting from bitscrambling. That is, the dummy bit size K0 is determined from thespecified code rate R, and using the result of comparison of themagnitudes of the total size K1 (=K+K0) of the information bit size Kand dummy bit size K0 with a stipulated size Z, a judgment is made as towhether to perform code block segmentation. In turbo encoding,40≦K1≦5114, so that Z=5114.

If the dummy bit size is K0 and the information bit size is K, then inthe case of turbo encoding, when dummy bits are deleted and the data istransmitted, the code rate R is

R=K/{K+2(K+K0)}  (1)

so that from the above equation, the dummy bit size K0 is calculated tobe

K0=(K−3KR)/2R  (2)

When the total size K1 (=K+K0) exceeds the stipulated size Z, the codeblock segmentation portion 23 determines the number of code blocks C andthe code block size, and segments the data set D2 to obtain C (in thefigure, C=2) code blocks 1, 2, which are a plurality of code blocks allof the same size ((a) in FIG. 2). When the data cannot be divided by thenumber of code blocks, filler bits are inserted to adjust the size.Filler bits have value “0”, and are inserted at the beginning of theoriginal data.

The dummy bit insertion portion 31 inserts dummy bits of size K0/2 intoeach code block ((b) in FIG. 2), the encoding portion 24 performsencoding, such as for example turbo encoding, of each code block withthe dummy bits inserted ((c) of FIG. 2).

The bit segmentation portion 25 a of the physical layer HARQ functionportion 25 divides the code of each of the code blocks output from theencoding portion 24 into (1) systematic bits+dummy bits, (2) parity bits1, and (3) parity bits 2, and concatenates bits of the same type (see(a) in FIG. 3). Then, the first rate matching portion 25 b of thephysical layer HARQ function portion 25 checks to determine whether thetotal bit length of data set D5 is greater than the stipulated buffersize NIR, and if greater, performs puncturing of parity bits 1 andparity bits 2 so that the size is the same as NIR, and at the same timedeletes the dummy bits from the systematic bits ((b) in FIG. 3).

Next, the second rate matching portion 25 c of the HARQ function portion25 performs rate matching (repetition or puncturing) of the data set D61of systematic bits and parity bits 1, 2 shown in (b) of FIG. 3,according to the specified H-ARQ transmission parameters. Thereafter,processing similar to that of the prior art is performed, and systematiccode with the dummy bits deleted is transmitted. On the receiving side,the systematic code is received, then the dummy bits deleted on thetransmitting side are inserted, as maximum-likelihood values, into thereceived systematic code, and thereafter turbo decoding is performed toobtain the information bits. In HSDPA, the information necessary forreception (address, modulation method, dummy bit size, dummy bitinsertion method, and similar) is transmitted to the reception device inadvance as necessary through the shared channel HS-SCCH. Hence in thereception device the positions of dummy bit insertion on thetransmitting side are known, and so maximum-likelihood dummy bits areinserted at these positions and decoding is performed.

FIG. 4 shows the configuration of the code block segmentation portion23; the dummy bit size calculation portion 23 a calculates the size K0of dummy bits based on the specified code rate R using the equation (2),the code block number/code block size judgment portion 23 b decides thenumber of code blocks and the code block size based on the total size K1(=K+K0) of the information bit size K and dummy bit size K0 as well asthe stipulated size Z, the segmentation portion 23 c segments thebit-scrambled data set D2 into the specified number of segments, thedummy bit insertion portion 31 inserts K0/2 dummy bits into each codeblock, and the encoding portion 24 performs encoding of each of the codeblocks with dummy bits inserted.

By means of the first embodiment, the dummy bits are inserted into theinformation bits, then parity bits are added to the information bitsinto which the dummy bits are inserted by turbo encoding, thereafter thedummy bits are deleted from the turbo code to obtain systematic codewhich is transmitted; on the receiving side, the systematic code isreceived, then the dummy bits deleted on the transmitting side areadded, as maximum-likelihood values, to the received systematic code,and thereafter turbo decoding is performed, so that decoding errors canbe reduced.

Further, by means of the first embodiment, because the dummy bits arealready separated from the systematic bits in the dummy bit deletionportion 25 b-3, deletion of dummy bits from the systematic bits caneasily be performed. Moreover, dummy bit deletion can be performedsimultaneously with puncturing of the parity bits 1 and 2, so that dummybit deletion does not affect the overall transmission processing time.

Modified Example

In the above, a case was explained in which the dummy bits are deletedin the dummy bit deletion portion 25 b-3 of the physical layer HARQfunction portion 25; however, deletion can also be performed within theturbo encoder. FIG. 5 shows the configuration of a turbo encoder 24; 24a is a first element encoder which encodes information bits into whichdummy bits have been inserted, 24 b is an interleaving portion whichinterleaves information bits into which dummy bits have been inserted,24 c is a second element encoder which encodes the interleaving result,24 d is a dummy bit deletion portion which deletes dummy bits, and 24 eis a P/S conversion portion which converts the outputs of the elementencoders 24 a, 24 b and the dummy bit deletion portion 24 d into serialdata. By deleting dummy bits within the turbo encoder as explainedabove, the dummy bits can easily be deleted from the systematic bits.

(B) Second Embodiment

In the second embodiment, dummy bits are inserted such that the coderate is a fixed value to perform encoding, and the entire bit size ofthe transmission data is fixed at Ndata. Here however Ndata is equal tothe number of codes times the physical channel size.

FIG. 6 explains dummy bit processing in the wireless base station of thesecond embodiment; the configuration of the transmission processingportion is the same as that of the first embodiment in FIG. 1.

Similarly to the first embodiment, the code block segmentation portion23 performs code block segmentation of the data set D2 which has beensubjected to bit-scrambling. That is, the dummy bit size K0 resulting inthe stipulated code rate R is determined, and by comparing themagnitudes of the total size K1 (=K+K0) of the information bit size Kand dummy bit size K0 with the stipulated size Z, a judgment is made asto whether code block segmentation is necessary, and code blocksegmentation is performed ((a) in FIG. 6).

The dummy bit insertion portion 31 inserts K0/2 dummy bits into eachcode block ((b) in FIG. 6), and the encoding portion 24 performsencoding of each code block with dummy bits inserted, by for exampleperforming turbo encoding ((c) in FIG. 6).

The first rate matching portion 25 b of the physical layer HARQ functionportion 25 checks whether the code bit length is greater than thestipulated buffer size NIR, and if greater, performs puncturing ofparity bits 1 and parity bits 2 such that the size is the same as NIR,and simultaneously deletes dummy bits from the systematic bits. Then,the second rate matching portion 25 c of the physical layer HARQfunction portion 25 performs rate matching (repetition or puncturing)such that the code length is equal to Ndata ((d) in FIG. 6).

Thereafter, processing similar to that of the prior art is performed,and systematic code not containing dummy bits is transmitted. On thereceiving side, the systematic code is received, the dummy bits deletedon the transmitting side are inserted into the systematic code asmaximum-likelihood values, turbo decoding is performed, and theinformation bits are acquired.

FIG. 7 is a block diagram of principal portions of the transmissionprocessing portion of the second embodiment; portions which are the sameas in the first embodiment of FIG. 4 are assigned the same symbols. Adifference is the addition of a physical layer HARQ function portion 25,having a dummy bit deletion portion and a second rate matching portion.

FIG. 8 shows the flow of dummy bit insertion processing in the secondembodiment. The size K0 of dummy bits is decided such that the code rateR is the stipulated rate (step 501), the total size K1 (=K+K0) of theinformation bit size K and dummy bit size K0 is calculated (step 502),the magnitudes of the total size K1 and the stipulated size Z arecompared (step 503), and if K1≦Z the code block is not segmented, and K0dummy bits are inserted into the information bits (step 504), and dummybit insertion processing ends. If on the other hand K1>Z, the number ofcode blocks/code block size are decided, and code block segmentation isperformed (step 505). Then, filler bits are inserted (step 506), andK0/C dummy bits are inserted into each code block (where C is the numberof code blocks; if C=2, then K0/2 dummy bits are inserted) (step 507),and dummy bit insertion processing ends.

FIG. 9 explains the dummy bit insertion method after code segmentation.When dummy bit are inserted, the dummy bit insertion positions and dummybit values (0,1) are made the same, such that the same number of dummybits are allocated uniformly to each of the code blocks.

By the way, FIG. 8 is for a case in which dummy bits are inserted aftercode block segmentation; when it is necessary to insert dummy bitsbefore code block segmentation and then perform segmentation, code blocksegmentation can be performed such that dummy bits are distributeduniformly to each of the code blocks. FIG. 10 shows the flow of dummybit insertion in this embodiment; the step of processing to insert dummybits (step 511) is positioned before step 503 to compare the magnitudesof the total size K1 and the stipulated size Z. FIG. 11 explains theinsertion method for inserting dummy bits prior to segmentation; dummybits are inserted such that there is no deviation in dummy bit placementof each code block, and moreover dummy bit insertion positions areuniform in each code block when code block segmentation is performed.

By means of the above second embodiment, the dummy bit size is decidedsuch that the required code rate is obtained, and moreover rate matchingcan be performed and data transmitted such that the Ndata given by theH-ARQ transmission parameters is achieved. And, by uniformly insertingdummy bits, decoding characteristics can be improved.

The dummy bit insertion method of FIG. 9 and FIG. 11 is not limited tothe second embodiment, but can be applied to all the embodiments.

(C) Third Embodiment

The third embodiment is an example in which dummy bits are inserted suchthat the code total bit length is equal to Ndata. FIG. 12 explains dummybit insertion processing in the third embodiment, and FIG. 13 shows theflow of dummy bit insertion processing; the configuration of thetransmission processing portion is the same as that of the firstembodiment in FIG. 1.

The code block segmentation portion 23 calculates the size K0 of dummybits to be inserted such that the total bit length is equal to Ndata(step 551). When dummy bits of size K0 are inserted into informationbits of size K, turbo encoding is performed, the dummy bits are deletedand the result is transmitted, the code size is K+2(K+K0). Hence theequation

Ndata=K+2(K+K0)  (3)

obtains, and the dummy bit size K0 is

K0=(Ndata−3K)/2  (4)

Next, the size K1=K+K0 of information bits with dummy bits inserted iscompared with the stipulated size Z (=5114) (step 552), and if K1≦Z,code block segmentation is not performed, and K0 dummy bits are insertedinto the information bits (step 553), and dummy bit insertion processingends. If on the other hand K1>Z, then the number of code blocks and codeblock size are decided, and code block segmentation is performed ((a) inFIG. 12; step 554). Then, filler bits are inserted (step 555), and K0/C(where C is the number of code blocks; if C=2, then K0/2) dummy bits areinserted into each code block ((b) in FIG. 12; step 556), and dummy bitinsertion processing ends.

The encoding portion 24 performs encoding of each code block with dummybits inserted, by for example performing turbo encoding ((c) in FIG. 12;step 557). Then, the physical layer HARQ function portion 25 deletes thedummy bits from the systematic bits ((d) in FIG. 12; step 558). The codelength after deleting the dummy bits is equal to Ndata, and so thephysical layer HARQ function portion 25 does not perform rate matching(repetition or puncturing).

Thereafter, processing similar to that of the prior art is performed,and systematic code with dummy bits deleted is transmitted. On thereceiving side, the systematic code is received, the dummy bits whichhad been deleted on the transmitting side are inserted into the receivedsystematic code as maximum-likelihood values, and turbo decoding isperformed to obtain the information bits.

In the third embodiment, dummy bits can be inserted and transmission isperformed such that the code rate R (=K/Ndata) is variable, and moreoversuch that the code length is equal to Ndata.

(D) Fourth Embodiment

The fourth embodiment is an embodiment in which code block segmentationis not performed (the number of code blocks is 1). FIG. 14 explainsdummy bit insertion processing in the fourth embodiment; FIG. 15 showsthe flow of dummy bit insertion processing, in which the transmissionprocessing portion has the same configuration as in the first embodimentin FIG. 1.

When the size K1 (=K+K0) resulting from combining the dummy bit size K0determined from the specified code rate and the information bit size Kexceeds a stipulated size Z, in the fourth embodiment, the dummy bitsize is adjusted such that the total size K1 is equal to the stipulatedsize Z.

The code block segmentation portion 23 decides the dummy bit size K0using equation (2) such that the code rate is the stipulated code rate R(step 601), calculates the total size K1 (=K+K0) of the information bitsK and dummy bit K0 (step 602), and compares the magnitudes of the totalsize K1 and the stipulated size Z (step 603).

If K1≦Z, dummy bits of size K0 are inserted into the information bits ofsize K ((a) in FIG. 14; step 604). On the other hand, if K1>Z, theamount ΔK by which the stipulated size Z is exceeded is calculated usingthe equation

ΔK=K1−Z  (5)

and the dummy bit size K0 is modified according to the equation

K0=K0−ΔK

(step 605). Then, dummy bits of size K0 are inserted into theinformation bits of size K ((a) in FIG. 14; step 604).

When the above dummy bit insertion processing is completed, the encodingportion 24 encodes the code block with dummy bits inserted, by forexample performing turbo encoding ((b) in FIG. 14; step 606). And, thephysical layer HARQ function portion 25 deletes the dummy bits from thesystematic bits, and performs rate matching such that the code length isequal to Ndata ((c) in FIG. 14; step 607).

Thereafter processing similar to that of the prior art is performed, andsystematic code without dummy bits is transmitted. On the receivingside, the systematic code is received, the dummy bits which had beendeleted on the transmitting side are inserted into the receivedsystematic code as maximum-likelihood values, turbo decoding isperformed, and the information bits are obtained.

By means of the fourth embodiment, the maximum number of dummy bits canbe inserted and the code length made equal to Ndata to performtransmission even when code block segmentation is not performed.Consequently, the effect of dummy bit insertion can be enhanced in acase where code block segmentation is not performed.

(E) Fifth Embodiment

The fifth embodiment is an embodiment in which, when code blocksegmentation is performed, the dummy bit size is decided such that thetotal size in each code block of dummy bits and information bits is astipulated size Z. FIG. 16 explains the dummy bit insertion processingof the fifth embodiment, and FIG. 17 shows the flow of dummy bitinsertion processing; the configuration of the transmission processingportion is the same as in the first embodiment of FIG. 1.

The code block segmentation portion 23 decides the dummy bit size K0using equation (2) such that the code rate is the stipulated code rate R(step 651), calculates the total size K1 (=K+K0) of the information bitsize K and dummy bit size K0 (step 652), and compares the magnitudes ofthe total size K1 and the stipulated size Z (step 653).

If K1≦Z, K0 dummy bits are inserted into the information bits of size K(step 654). Moreover, dummy bits can be inserted such that the codeblock size is the stipulated size Z.

On the other hand, if K1>Z, the number of code blocks and code blocksize are decided, and code block segmentation is performed ((a) in FIG.16; step 655). Then, filler bits are inserted (step 656), dummy bits areinserted such that the size of each code block is equal to thestipulated size Z ((b) in FIG. 16; step 657), and the dummy bitinsertion processing ends.

The encoding portion 24 performs turbo encoding, for example, of each ofthe code blocks with dummy bits inserted ((c) in FIG. 16). The physicallayer HARQ function portion 25 deletes the dummy bits from thesystematic bits, and performs rate matching such that the code length isequal to Ndata.

Thereafter, processing similar to that of the prior art is performed,and systematic code without dummy bits is transmitted. On the receivingside, the systematic code is received, the dummy bits which had beendeleted on the transmitting side are inserted into the receivedsystematic code as maximum-likelihood values, turbo decoding isperformed, and the information bits are obtained.

By means of the fifth embodiment, dummy bits are inserted such that thetotal size of dummy bits and information bits in each code block isequal to the stipulated size Z, encoding is performed, the dummy bitsare deleted, and the data is transmitted. In this case, the size of theinserted dummy bits can be made large, so that the effect of dummy bitinsertion can be enhanced.

(F) Sixth Embodiment

The sixth embodiment is an embodiment in which dummy bits are insertedbefore bit scrambling; FIG. 18 explains dummy bit insertion, FIG. 19 isa block diagram of principal portions of the transmission processingportion, and FIG. 20 shows the flow of dummy bit insertion processing.

The dummy bit size calculation portion 31 a of the dummy bit insertionportion 31 decides the dummy bit size K0 using equation (2) such thatthe code rate is the stipulated code rate R (step 701) and calculatesthe total size K1 (=K+K0) of the information bit size K and dummy bitsize K0 (step 702), and the dummy bit insertion portion 31 b inserts,into the information bits ((a) of FIG. 18) with CRC bits added by theCRC addition portion 21, all-“0”s dummy bits ((b) in FIG. 18; step 703).Dummy bits need not be all-“0”s bits.

Next, the bit scrambling portion 22 performs bit scrambling ofinformation bits with dummy bits inserted, and inputs the result to thecode block segmentation portion 23 ((c) in FIG. 18; step 704).

The code block number/code block size judgment portion 23 b of the codeblock segmentation portion 23 compares the magnitudes of the size K1(=K+K0) of the bit-scrambled data set D2 (the total size of theinformation bits and dummy bits) and a stipulated size Z (step 705).

If K1≦Z, code segmentation is not performed; if on the other hand K1>Z,the number of code blocks and code block size are decided, and thesegmentation portion 23 c performs code block segmentation (step 706).Then, filler bits are inserted (step 707).

Thereafter, similarly to the first embodiment, the encoding portion 24performs turbo encoding of each of the code blocks with dummy bitsinserted, and the physical layer HARQ function portion 25 deletes dummybits and performs prescribed rate matching, and transmits systematiccode without dummy bits. On the receiving side, the systematic code isreceived, the dummy bits which had been deleted on the transmitting sideare inserted as maximum-likelihood values into the received systematiccode, turbo decoding is performed, and the information bits areobtained.

By means of the sixth embodiment, dummy bits can be inserted prior tobit scrambling.

(G) Seventh Embodiment

The seventh embodiment is an embodiment in which dummy bits are insertedafter bit scrambling; FIG. 21 explains dummy bit insertion, FIG. 22 is ablock diagram of principal portions of the transmission processingportion, and FIG. 23 shows the flow of dummy bit insertion processing.

The bit scrambling portion 22 performs bit scrambling ((b) in FIG. 21;step 751) of the information bits ((a) in FIG. 21) with CRC bits addedby the CRC addition portion 21. Then, the dummy bit size judgmentportion 31 a of the dummy bit insertion portion decides the dummy bitsize K0 using equation (2), such that the code rate is the stipulatedcode rate R (step 752), calculates the total size K1 (=K+K0) of theinformation bit size K and dummy bit size K0 (step 753), and the dummybit insertion portion 31 b inserts all-“1”s dummy bits of size K0 intothe bit-scrambled information bits ((c) of FIG. 21; step 754). Here,all-“0”s dummy bits are inappropriate.

The code block number/code block size judgment portion 23 b of the codeblock segmentation portion 23 compares the magnitudes of the total sizeK1 of information bits and dummy bits with the stipulated size Z (step755). If K1≦Z, code block segmentation is not performed; but if K1>Z,the number of code blocks and code block size are decided, and thesegmentation portion 23 c performs code block segmentation (step 756).Then, filler bits are inserted (step 757).

Thereafter, similarly to the first embodiment, the encoding portion 24performs turbo encoding of each of the code blocks with dummy bitsinserted, and the physical layer HARQ function portion 25 deletes dummybits and performs prescribed rate matching, and transmits the systematiccode without dummy bits. On the receiving side, the systematic code isreceived, the dummy bits which had been deleted on the transmitting sideare inserted into the received systematic code as maximum-likelihoodvalues, turbo decoding is performed, and the information bits areobtained.

In the above, an example was explained in which the dummy bit insertionportion 31 inserts all-“1”s dummy bits; but as shown in (c) of FIG. 24,the dummy bit values can be made a random pattern.

By means of the seventh embodiment, dummy bits can be inserted after bitscrambling.

(H) Eighth Embodiment

The eighth embodiment is an embodiment of dummy bit insertion patternsin the information bits. As an insertion pattern, a pattern in whichsystematic bits and dummy bits are alternated as shown in (a) of FIG. 25can improve decoding characteristics compared with a pattern in whichdummy bits are placed together before and after the information bits.

However, an alternating placement pattern is for a case in which thesizes of the systematic bits and dummy bits are the same; when the sizesare different, alternating placement is not possible. Hence dummy bitsare inserted into systematic bits with dummy bits of only a specifiedcontinuous length allowed. Even when the continuous length of dummy bitsis made less than or equal to a preset value, with dummy bits placed indispersed positions, decoding characteristics (decoding errorcharacteristics) can be improved. For example, when information bits anddummy bits are the same size, and the continuous length is 2, twoinformation bits and two dummy bits are placed in alternation as shownin (b) in FIG. 15. When the continuous length is 3, three informationbits and three dummy bits are placed in alternation as shown in (c) inFIG. 15.

Further, as shown in FIG. 26, a pattern is possible in which dummy bitsare not inserted on the periphery STA and TLA at the beginning and atthe end of the information. This is because in Viterbi decoding and MAPdecoding, the reliability of code at the beginning and at the end of theinformation is sufficiently high. Hence as shown in FIG. 26, dummy bitsare dispersed and inserted in the area excluding the periphery STA andTLA at the beginning and end of the information.

Further, based on the internal interleave pattern of the turbo encoding,bit positions A1 to A4 which move to a stipulated number of positions atthe beginning and end of the information by interleaving processing arespecified in advance, as shown in FIG. 27. Dummy bits are likewise notinserted into these positions A1 to A4 either. The reason for this isthe same as that of FIG. 26.

(I) Ninth Embodiment

3GPP turbocodes have the characteristic when the code rate reaches aspecific value due to puncturing or similar, the characteristicdegradation is locally large compared with the peripheral code rates.FIG. 28 explains this characteristic degradation; A is the decodingcharacteristic when there is no dummy bit insertion, in which thehorizontal axis is the code rate, and the vertical axis is the requiredEb/No to obtain a prescribed error rate. As is clear from the decodingcharacteristic, when the code rate reaches a specific value ( 7/11, 7/9,⅞), the required Eb/No becomes large compared with the peripheral coderate, and the characteristic is degraded. Hence in the ninth embodiment,monitoring is performed to determine whether the code rate afterpuncturing has reached a value close to a specific value (a value in aspecific range S1, S2, S3), and if the value is in a specific range S1,S2, S3, dummy bits are inserted prior to puncturing, thereby thedecoding characteristic is shifted as indicated by B, and the code rateassumes a value outside the specific ranges S1′, S2′, S3′ determined bythe decoding characteristic B is performed, to prevent characteristicdegradation. The dummy bit insertion amount is determined such that thecode rate exists just outside the periphery of the peak in thecharacteristic B after shifting.

FIG. 29 shows the configuration of the transmission processing portionin the wireless base station of the ninth embodiment; the transmissionprocessing portion 30 comprises a CRC addition portion 21, bitscrambling portion 22, code block segmentation portion 23, dummy bitinsertion control portion 41, channel coding portion (encoding portion)24, physical layer HARQ function portion 25, physical channelsegmentation portion 26, HS-PDSCH interleaving portion 27, constellationrearrangement portion 28, physical channel mapping portion 29, andtransmission portion (not shown).

The dummy bit insertion control portion 41 is provided between the codeblock segmentation portion 23 and the encoding portion 24, and executescontrol to determine whether, based on the code rate, dummy bits areinserted into information bits. That is, the dummy bit insertion controlportion 41 calculates the code rate R taking into account puncturing inthe physical layer HARQ function portion 25 (step 801). If theinformation bit length is K, the parity bit length for systematic codeobtained by encoding of the information is M, and the number ofpuncturing bits is P, then the code rate R is

R=K/(K+M−P)

In the case of turbo encoding, M=2K, so that R=K/(3K−P).

The dummy bit insertion control portion 41 checks whether the calculatedcode rate R is a value within the ranges S1, S2, S3, centered on thespecific values 7/11, 7/9, ⅞ respectively and of width±Δ (step 802). Ifnot a value in these ranges, the dummy bit insertion control portion 41does not insert dummy bits; but if the value is within these ranges,dummy bits are inserted into information bits such that the decodingcharacteristic is shifted from A to B and the code rate assumes a valueoutside the specific ranges S1′, S2′, S3′ (step 803).

By means of the ninth embodiment, dummy bits are inserted such that thecode rate does not assume a value in specific ranges which causedegradation of the decoding characteristic, so that degradation of thedecoding characteristic can be prevented.

(J) Tenth Embodiment

When using turbocodes for encoding, if the dummy bit insertion positionpatterns are made as uniform as possible in both the input bits (calledthe “first input” and “second input” respectively) to the first elementencoder and second element encoder of the turbo encoding portion,decoding characteristics can be improved.

For this reason, efforts are made to avoid positioning other dummy bitsinsofar as possible within several bits before and after a dummy bitinsertion position. That is, when the number of information bits is Kand the number of dummy bits is K0, and when K0≦K, in both the first andsecond inputs an ideal arrangement is used in which dummy bits are notmade adjacent, and moreover the dummy bit insertion positions in boththe first and second inputs are equal. Further, when K0>K, an idealarrangement is used in which information bits are not made adjacent inboth the first and second inputs, and moreover the information bitinsertion positions in both the first and second inputs are equal. WhenK0>K and dummy bits are more numerous than information bits, inprinciple at least two dummy bits are adjacent. In this case, uniformityis realized by interchanging the roles of the dummy bits and theinformation bits.

When the ratio of K0 to K is not an integer, and when such anarrangement is not possible due to a positional relationship resultingfrom interleaving, interchanging of dummy bit positions and informationbit positions is allowed. However, this interchanging is performedsubstantially equally for each of the first and second inputs.

For example, as shown in (A) in FIG. 30, when K=K0, completely uniformarrangement is performed for the first input (alternating arrangement),and the interleaving pattern P is employed to generate the second input.In the second input, a search is performed for portions in which thedummy bit burst length (continuous length) is 3 or more, and if suchportions exist, a dummy bit position d is determined such that, when thedummy bit is changed to an information bit, the burst length becomes 1or 2. Then, the position in the first input corresponding to this dummybit position d is determined from Q(d). Here Q is the deinterleavingpattern, and P(Q(d))=d. In the first input, the positions Q(d)±1adjacent on both sides of the position Q(d) are currently informationbits; and when a dummy bit is inserted at each of bit positions(P(Q(d)+1), P(Q(d)−1) in the second input corresponding to the bitpositions Q(d)±1 in the first input, the bit position (in the figure,P(Q(d)+1) is selected for which the generated dummy bit burst length isshorter. And, as shown in (B) in FIG. 30, the dummy bit at position Q(d)and the information bit at position Q(d)+1 in the first input areinterchanged. That is, position Q(d) in the first input is changed froma dummy bit to an information bit, and position Q(d)+1 is changed froman information bit to a dummy bit. By this means, the continuous lengthof dummy bits in the second input after interleaving can be kept to 2 orless.

FIG. 31 shows the flow of an efficient algorithm to modify dummy bitpositions so as to satisfy the condition explained in FIG. 30. Supposethat the input information bit size is K, the dummy bit size is K0, andthe combined bit size is K1, so that K1=K+K0. Further, P(i), Q(i) arerespectively the interleaving pattern and the inverse thereof(deinterleaving pattern). That is, Q(P(i))=i. Further, suppose that thenumber of dummy bits of which positions have been determined is Nd, andthat the threshold for position judgment is Th=10. Moreover, weightingcoefficients W(i) are associated with each bit position i as shown inFIG. 32.

First, a counter is initialized to Nd=0, and all weighting coefficientsW(i) are initialized to 0 (step 901).

Then, the following operation is repeated iteratively for i=0 to K1−1.That is, with i=0, if i<K1 (steps 902 to 903), a check is performed asto whether W(i)≦Th (step 904). If W(i)≦Th, the position i is made adummy bit position (step 905), and the weighting coefficient is updatedas indicated below (step 906).

W(i)=300 W(i+1)+50=W(i+1) W(i−1)+50=W(i−1) W(i+2)+10=W(i+2)W(i−2)+10=W(i−2) W(Q(P(i)+1))+50=W(Q(P(i)+1))W(Q(P(i)−1))+50=W(Q(P(i)−1)) W(Q(P(i)+2))+10=W(Q(P(i)+2))W(Q(P(i)−2))+10=W(Q(P(i)−2))

Here, when x<0 or x≧K1 in regard to W(x), no processing is performed.

Next, the number Nd of dummy bits for which positions have beendetermined is incremented (Nd+1=Nd; step 907), and a check is performedas to whether Nd<K0 (step 908); if Nd≧K0, processing ends, and if Nd<K0then i is advanced (step 909) and the processing of step 903 and beyondis continued. In step 904, if W(i)>Th, i is immediately advanced (step909), and the processing of step 903 and beyond is continued.

On the other hand, in step 903, when i=K1 a check is performed as towhether Nd<K0 (step 910), and if Nd≧K0 processing ends, but if Nd<K0,Wmin is made the smallest value of W(i) (step 911), and then Th is setequal to Wmin+20 (step 912), and the processing of step 902 and beyondis repeated.

There are cases in which problems may arise when employing the method,which has been the basis of the embodiments thus far, of uniformlyinserting dummy bits into the input information bits. For example, whenturbo encoding is adopted, the input of the second element encoder ofthe turbo encoding portion is a pattern resulting from interleaving. Forthis reason, if dummy bits are simply inserted uniformly intoinformation bits prior to interleaving, the positions of the dummy bitschange due to interleaving, and so the dummy bit positions of the secondinput of the second element encoder are no longer uniform. As a result,an undesirable pattern (with long continuations of dummy bits) occurs inthe second input, causing degradation of decoding characteristics. Onthe other hand, in the tenth embodiment, the above-described algorithmis used to decide dummy bit insertion positions such that dummy bitcontinuous lengths are not long. That is, the dummy bit insertionpositions are decided one by one, and the weightings of the adjacent andnext-adjacent positions of the dummy bits are increased in both thefirst and second inputs, so that such positions are not easily selectedas dummy bit positions; by this means, dummy bit continuous lengths arekept from becoming long.

Moreover, algorithms are not limited to that described above; anyalgorithm which arranges dummy bit insertion position patterns asuniformly as possible in both the first and second inputs can be adoptedin the tenth embodiment.

In the above, a method of deciding the dummy bit size K0 was notexplained; but as explained in the second embodiment, the size of thedummy bits to be inserted into information bits is decided based on thespecified code rate. Or, as explained in the third embodiment, the sizeof dummy bits K0 is calculated such that the code size is equal to thebit length Ndata determined by the physical channel transmission rate.

(K) Eleventh Embodiment

It is known that in many cases, arrangement of the dummy bit insertionpositions at the inputs to both the first element encoder and the secondelement encoder of the turbo encoding portion so as to be as widelydispersed overall as possible is effective for improvingcharacteristics. The method of the tenth embodiment to realize such anarrangement has the problem of employing a position generation algorithmwhich is complex and requires large amounts of processing and longprocessing time. In the eleventh embodiment, the dummy bit insertionpositions in both the first and second inputs of the first and secondelement encoders are simply made as widely dispersed overall aspossible.

FIG. 33 shows the configuration of the turbo encoder of the eleventhembodiment; the first element encoder 24 a encodes information bits withdummy bits inserted, the interleaving portion 24 b interleaves theinformation bits with dummy bits inserted, the second element encoder 24c encodes the result of interleaving, and the P/S conversion portion 24e converts the outputs xb, xc of the element encoders 24 a, 24 b and theinformation bits xa into series data. The first and second dummy bitinsertion portions 51, 52 insert dummy bits into the first and secondinputs, which are the inputs of the first and second element encoders 24a, 24 b. It is preferable that the dummy bits be inserted into both thefirst and the second inputs so as to be widely dispersed overall, and soas to be as uniform as possible.

The size of dummy bits for insertion K0 is, as explained in the secondembodiment, based on a specified code rate and calculated using equation(2), or is, as explained in the third embodiment, calculated usingequation (4) such that the code length is equal to the bit length Ndatadetermined by the physical channel transmission rate.

In the configuration of FIG. 33, two element encoders are provided;however, a single element encoder can perform the first and secondelement encoding processing.

FIG. 34 shows the configuration of the turbo decoder portion on thereceiving side which decodes the turbocode encoded by the encoder ofFIG. 33, wherein first and second dummy bits are same as the first andsecond dummy bits in the encoder.

The first element decoder 61 uses ya and yb among the received signalsya, yb, yc to perform decoding. The first element decoder 61 is asoft-decision output element decoder, which outputs decoding resultlikelihoods. The first dummy bit deletion portion 62 deletes the firstdummy bits from the decoding result of the first element decoder 61, theinterleaving portion 63 interleaves the decoding result with dummy bitsdeleted, and the second dummy bit insertion portion 64 inserts seconddummy bits into the interleaved decoding results as maximum-likelihoodvalues.

The second element decoder 65 performs decoding using the receivedsignal yc and the decoding result of the first element decoder 61, whichhas been subjected to interleaving and second dummy bit insertionprocessing. The second element encoder 65 is also a soft-decision outputelement decoder, which outputs decoding result likelihoods. The seconddummy bit deletion portion 66 deletes the second dummy bits from thedecoding output of the second element decoder 65, the deinterleavingportion 67 deinterleaves the decoding result with the dummy bitsdeleted, and the first dummy bit insert portion 68 inserts the firstdummy bits as maximum-likelihood values into the deinterleaved decodingresults, and inputs the results to the first element decoder 61. Inplace of the received signal ya, the first element decoder 61 uses theoutput signal of the first dummy bit insertion portion 68 to repeat theabove MAP decoding processing. By repeating the above decoding operationa prescribed number of times, the decoding result error rate can bereduced. MAP element decoders are used as the first and second elementdecoders in this turbo element decoder.

The above processing to delete and add maximum-likelihood reliabilitiesfor dummy bit data is performed in order that a trellis path limited bythe dummy bit values is selected; in place of this insertion anddeletion, the trellis path can also be selected directly.

In the configuration of FIG. 34, two element decoders are provided; buta single element decoder can perform the first and second elementdecoding. Similarly, a single dummy bit deletion portion and a singledummy bit insertion portion can be made to perform the first and seconddummy bit deletion processing and the first and second dummy bitinsertion processing.

By means of the eleventh embodiment, insertion positions can be mademutually independent in both the inputs to the first element encoder 24a and to the second element encoder 24 c; in particular, patterns whichare uniform overall can be selected for both. Moreover, a dummy bitdeletion portion becomes unnecessary.

(L) Advantageous Results of the Invention

As explained above, according to this invention, dummy bits are insertedinto information bits, then the information bits into which the dummybit inserted are subjected to turbo encoding, and the systematic codeobtained by deleting the dummy bits from the turbocode is transmitted;on the receiving side, the systematic code is received, the dummy bitswhich had been deleted on the transmitting side are inserted into thereceived systematic code as maximum-likelihood values, and turbodecoding is performed, and by this means decoding errors can be reduced.

Further, according to this invention, by providing a dummy bit deletionportion in the physical layer HARQ function portion or in the encodingportion, the dummy bits can easily be deleted from systematic bits.Further, according to this invention, processing to delete dummy bitsfrom systematic bits can be performed simultaneously with puncturingprocessing of parity bits of the systematic code. Consequently, dummybit deletion can be performed so as not to affect the total transmissionprocessing time.

According to this invention, the size of dummy bits is decided so as toobtain a required code rate, and moreover rate matching can be performedand data is transmitted such that Ndata is the value given by H-ARQtransmission parameters. Further, by uniformly inserting dummy bits,decoding characteristics can be improved.

According to this invention, dummy bits can be inserted and data istransmitted with the code rate R made variable, and such that the codelength is equal to Ndata.

According to this invention, even when code block segmentation is notperformed, the maximum number of dummy bits can be inserted, and thecode length can be made equal to Ndata to transmit the data. As aresult, even when code block segmentation is not performed, the effectof dummy bit insertion can be improved.

According to this invention, dummy bits can be inserted, encodingperformed, the dummy bits deleted from the results of the encoding, andthe data is transmitted such that, in each code block, the total size ofthe dummy bits and information bits is equal to a stipulated size Z;hence the size of the inserted dummy bits can be made large, so that theeffect of dummy bit insertion can be improved.

According to this invention, dummy bit insertion can be performed eitherbefore bit scrambling or after bit scrambling.

According to this invention, dummy bits are dispersed and inserted intoinformation bits with dummy bit continuous lengths equal to or less thana set value, so that decoding characteristics can be improved. Further,dummy bits are dispersed and inserted into information bits excludingthe peripheral portions at the beginning and end of the informationbits, so that decoding characteristics can be improved. Further, when acode is adopted which requires interleave processing, dummy bits aredispersed and inserted at the bit positions which do not move to thebeginning and end of information by interleaving, so that decodingcharacteristics can be improved.

According to this invention, dummy bits are inserted such that the coderate does not assume a specific value which causes degradation of thedecoding characteristic, so that degradation of the decodingcharacteristics can be prevented.

According to this invention, when turbo encoding is adopted, thepatterns of dummy bit insertion positions are made as uniform aspossible in both the first and the second inputs, which are the inputsto the first element encoder and to the second element encoder, so thatdecoding characteristics can be improved.

According to this invention, when turbo encoding is adopted, dummy bitinsertion positions can be determined without mutual dependence of thefirst and second inputs of the first element encoder and second elementencoder, so that dummy bit insertion position patterns can easily bemade uniform in the first and second outputs, and decodingcharacteristics can be improved.

And, according to this invention, within the turbo encoder dummy bitsare inserted and parity bits generated, and moreover turbocode can beoutput without inserting dummy bits into systematic bits, so that adummy bit deletion portion to delete dummy bits from systematic bits canbe made unnecessary.

1. A transmission method for use in a communication system in which asystematic code obtained by systematic encoding of information bits intowhich dummy bits are inserted and by deletion of the dummy bits fromresults of the systematic encoding is transmitted and, on a receivingside, the dummy bits deleted on a transmitting side are inserted intothe received systematic code and then decoding is performed, thetransmission method comprising: deciding a size of dummy bits forinsertion into information bits based on a specified code rate,transmission rate or bit length which determines the transmission rate;segmenting the information bits into a number of code blocks when a bitsize of the information bits to which dummy bits are inserted is greaterthan a stipulated size; inserting dummy bits into each block of thesegmented information bits in conformity with a predetermined dummy bitinsertion pattern; performing systematic encoding of each block of theinformation bits into which the dummy bits are inserted, and alsodeleting the dummy bits from the results of the systematic encoding togenerate a systematic code; and transmitting the systematic code.
 2. Thetransmission method according to claim 1, wherein when the dummy bitsize is decided based on a specified code rate, and further comprising:performing rate matching processing such that the total size of thesystematic code from which the dummy bits are deleted is equal to thesize determined by the physical channel transmission rate.
 3. Thetransmission method according to claim 1, wherein the dummy bitinsertion portion decides the dummy bit size such that the total size ofthe segmented information bits and the inserted dummy bits is equal to astipulated size.
 4. The transmission method according to claim 1,wherein the dummy bit insertion portion inserts the same number of dummybits in the same positions in each block of the segmented informationbits.
 5. The transmission method according to claim 2, wherein the dummybits are inserted uniformly into each block of the segmented informationbits, and inserts the same number of dummy bits in the same positions ineach block of the segmented information bits.
 6. A communication systemwhich a systematic code obtained by systematic encoding of informationbits into which dummy bits are inserted and by deletion of the dummybits from results of the systematic encoding is transmitted and, on areceiving side, the dummy bits deleted on a transmitting side areinserted into the received systematic code and then decoding isperformed, the communication system comprising: a transmitting device;and a receiving device, wherein the transmitting device includes, adummy bit size decision portion that decides a size of dummy bits forinsertion into information bits based on a specified code rate,transmission rate or bit length which determines the transmission rate;a segmentation portion that segments the information bits into a numberof code blocks when a total size of bits including the information bitsis greater than a stipulated size; a dummy bit insertion portion thatinserts dummy bits into each block of the segmented information bits inconformity with a predetermined dummy bit insertion pattern; asystematic code generation portion that performs systematic encoding ofeach block of the information bits into which the dummy bits areinserted, and also deleting the dummy bits from the results of thesystematic encoding to generate a systematic code; and a transmissionportion that transmits the systematic code to the receiving device.
 7. Acommunication method for use in a communication system in which asystematic code obtained by systematic encoding of information bits intowhich dummy bits are inserted and by deletion of the dummy bits fromresults of the systematic encoding is transmitted and, on a receivingside, the dummy bits deleted on a transmitting side are inserted intothe received systematic code and then decoding is performed, thecommunication method comprising: deciding, by a transmission device, asize of dummy bits for insertion into information bits based on aspecified code rate, transmission rate or bit length which determinesthe transmission rate; segmenting, by the transmission device, theinformation bits into a number of code blocks when a total size of theinformation bits to which the dummy bits are to be inserted is greaterthan a stipulated size; inserting, by the transmission device, dummybits into each block of the segmented information bits in conformitywith a predetermined dummy bit insertion pattern; performing, by thetransmission device, systematic encoding of each block of theinformation bits into which the dummy bits are inserted, and alsodeleting the dummy bits from the results of the systematic encoding togenerate a systematic code; and transmitting the systematic code fromthe transmission device to a receiving device.